Alex Arellano was beaten, shot and burned to death in 2009

Two Chicago teenagers were found guilty Monday in the slaying of a 15-year-old boy who refused to flash a gang sign when a group of gang members confronted him and his girlfriend in 2009, prosecutors said.

Alex Arellano who was burned, beaten and shot, was discovered in the backyard of a vacant home in the 3000 block of West 54th Place a day after he was killed May 1, 2009. On Monday, Jovanny Martinez and Erick Ortiz, both 19, were convicted of first-degree murder in Alex's slaying by Cook County Circuit Judge Maura Slattery Boyle, said state's attorney's office spokeswoman Tandra Simonton.

Alisa Campos, 25, and Edgar Silva, 22, are in prison after pleading guilty in connection with Alex's slaying, according to court and Illinois Department of Corrections records.

Alex was near Sacramento Avenue and 54th Place, heading to a friend's house with a group of girls, including his girlfriend, when he was confronted by two people on bicycles who asked about his gang affiliation. Alex responded that he didn't belong to a gang, and the bikers rode off.

A short time later, a carload of Latin Kings gang members, including the two who had been on bikes, pulled up in front of 3043 W. 54th Place. The group, wielding baseball bats, demanded the victim "throw up the crown," or show the symbol of the Latin Kings, and when Alex refused, they began to beat him with the bats, prosecutors said at the time charges were originally brought in the case.

Alex fled into the backyard of the vacant home, where the attackers followed and continued to beat him before shooting him once in the head, prosecutors said in 2009.

Martinez and Ortiz are next due in court for post-trial motions: Martinez on May 28 and Ortiz on May 29, Simonton said. A sentencing date has not been set.